Synthesis and characterization of poly(amide-imide)s containing 1,6-diamantane moieties in the main chain

A series of new poly(amide-imide)s were synthesized by direct polycondensation of the 1,6-bis(trimellitimido)diamantane (1) with various aromatic diamines in N-methyl-2-pyrrolidone (NMP) containing lithium chloride. The poly(amide-imide)s had inherent viscosities of 0.33 - 1.55 dL/g. The new polycyclic monomer 1 was synthesized from 1,6-diaminodiamantane with trimellitic anhydride. Dynamic mechanical analysis revealed polymers 3 a-c to have main transitions at 385 degrees C, 385 degrees C, and 330 degrees C, respectively. Moreover, these polymers were stable at high temperatures and maintained good mechanical properties (G' approximate to 10(8) Pa) up to temperatures close to the main transition well above 350 degrees C. Their 5% weight loss temperatures ranged from 421 to 448 degrees C in nitrogen, and from 417 to 426 degrees C in air. A glass transition of poly(amide-imide)s 3 was not observed. Poly(amide-imide)s 3 (except 3e) were soluble in NMP, pyridine, and o-chlorophenol. Some of the polymers (3a-c) could be cast into flexible films. Their cast films had tensile strengths ranging from 35.5 to 46.9 MPa, elongations at break from 5.8 to 7.5%, and initial moduli from 1.8 to 2.1 GPa.